Detection of Boson Peak and Fractal Dynamics of Protein by Terahertz Time-Domain Spectroscopy

Terahertz time-domain spectroscopy and low-frequency Raman scattering have been performed on the protein hen egg white lysozyme. The boson peak (BP), which is the universal dynamics of disordered materials, has been detected around 0.5 THz. On the other hand, fracton behavior, which is universal in the self-similar structure, has appeared above the BP frequency. How the fracton appeared in the infrared spectrum is explained using the fracton model and the universal infrared coupling coefficient model for disordered materials.